An 80-year-old woman was admitted to the hospital after a fall. Her prior history was notable for coronary artery disease status post percutaneous intervention, poorly controlled type 2 diabetes mellitus, congestive heart failure, hypothyroidism, and atrial fibrillation. She had had multiple mechanical falls in the past with cervical spine and right-sided rib fractures. She had no recent hospitalization in the last 90 days and has been living at home prior to presentation. There was no history of exposure to the farm animals. During this hospitalization, she developed progressive dyspnea and hypoxia. Computed tomography (CT) revealed a bilateral pleural effusion, right more than left, with diffuse interlobular septal thickening. Note was also made of a diffuse, mosaic-like attenuation of the lung parenchyma, likely related to air trapping or obstructive small airway disease. There was no pleural enhancement, septations, or air noted within the pleural space
(a) CT chest showing bilateral empyema (right more than left). (b) CT chest showing persistent bilateral empyema after attempted drainage through chest drains.
Blood cultures prior to initiation of antimicrobial therapy returned negative. Sputum culture was negative for bacteria, including acid-fast bacilli. Transthoracic echocardiography was unremarkable.
The patient was treated initially with levofloxacin and ampicillin/sulbactam for a pneumonia and parapneumonic pleural effusion. Despite antimicrobial therapy, her respiratory status continued to deteriorate and within 48 hours of hospitalization required endotracheal intubation and ventilatory support. A thoracentesis yielded 250 ml of pus (WBCs more than 50,000 with 95% neutrophils, elevated protein 3.6 g/dL (normal 0.0–2.4 g/dL), LDH 13461 IU/L, glucose 6 mg/dL, and pH 6.94). A right-sided thoracostomy was performed to facilitate evacuation of the empyema using a 32 French (F) thoracostomy tube. Postprocedure chest X-ray confirmed the optimal placement of the tube
Chest X-ray showing the right-sided chest tube (green arrows), positioned in the most dependent area.
Coagulase-negative staphylococcus (CoNS) has become an important cause of nosocomial infections. Common human isolates are
Author | Age/sex | Diagnosis | Tissue culture for |
Blood culture for |
Antibiotic resistance | Outcome | Animal exposure |
---|---|---|---|---|---|---|---|
Shields et al. [ |
80/M | Right great toe cellulitis | Positive | Not specified | Tetracycline resistance | Resolution with TMP-SMX | Not specified |
Tous Romero et al. [ |
60/M | Pyoderma left hand | Positive | Not specified | Not specified | Resolution with azithromycin | Positive |
Al Kline et al. [ |
65/M | Abscess, osteomyelitis right foot | Positive bone culture | Positive | Ampicillin, ciprofloxacin, clindamycin, oxacillin, penicillin, ceftriaxone | Resolution with IV vancomycin | Positive |
Vallianou et al. [ |
46/M | Vertebral osteomyelitis, native valve, endocarditis | Not specified | Positive | Methicillin | Resolution with IV vancomycin, teicoplanin, oral clindamycin | Positive |
Sturgess et al. [ |
77/F | Right pubic osteomyelitis | Not specified | Positive | Pan-sensitive | Resolution with flucloxacillin, fusidic acid | Not specified |
de Jesus et al. [ |
84/M | Septicemia, colon cancer | Not specified | Positive | Methicillin-sensitive | Died | Not specified |
de Jesus et al. [ |
41/M | Acute respiratory failure, ARDS, H/O HIV, IV drug abuse | Not specified | Positive | Methicillin-sensitive | Died | Not specified |
de Jesus et al. [ |
63/M | Pneumonia | CN staph in sputum | Positive for |
Not specified | Resolved with erythromycin, cefuroxime | Not specified |
de Jesus et al. [ |
58/M | Colon cancer, septicemia | Not specified | Positive | Methicillin-resistant | Resolved with vancomycin | Not specified |
Males et al. [ |
39/M | Right ankle, osteomyelitis, septic, arthritis | Positive | Positive | Pan-sensitive | Penicillin | Not specified |
The critical event in the establishing the pathogenicity includes formation of multilayered biofilm, especially in foreign body-associated infections caused by CoNS. Members of the genus Staphylococcus produce various proteinaceous and nonproteinaceous adhesins, to mediate attachment to host surfaces, such as plasma extracellular and matrix proteins or even host cells [
There are limited data available about how CoNS which are usually common pathogens in veterinary medicine are gaining pathogenicity in human hosts. There are some shared virulence factors with
Staphylococcal species | Common virulence factors | Clinical manifestations |
---|---|---|
|
Staphylococcal enterotoxins ( |
Gastrointestinal manifestations of diarrhea, nausea, vomiting, and enterocolitis. |
Tissue necrosis cytotoxin Panton–Valentine leukocidin ( |
Hospital-acquired pneumonia, infective endocarditis, and tissue necrosis | |
Methicillin-resistance gene ( |
Major contributing factor for increase in new methicillin-resistant strains | |
Exfoliative toxins ( |
Cutaneous manifestations of cellulitis | |
Toxic shock syndrome toxin-1 ( |
Septic shock and disseminated blood stream infections |
The challenging problem even after CoNS isolation and identification is the assessment of their clinical relevance. The major diagnostic question remains as to whether the CoNS isolate represents a contamination of the specimen, physiological colonization of the skin or mucus membranes, or a clinically significant infection. In our case, the absence of other microbiological data and the confidence in the sterile process of procuring the sample from pleural fluid warranted consideration of
While treating the pleural infections, clinicians need to be cognizant of the choice of antimicrobial therapy and relevant pharmacokinetics. Major factors that inhibit the penetration of antibiotics is the large-sized effusions/empyema, thickness of pleura, and the nature of antibiotic itself; acute inflammation is proven to be a supporting factor due to vasodilation [
Source control for septic patients remains the cornerstone of treatment along with optimal antimicrobial coverage. The MIST-2 study reiterated the fact where use of t-PA and DNase combination therapy in patients with pleural infection improved drainage of pleural empyema, resulting in reduction in hospital stay and need for thoracic surgery intervention [
All authors claim no conflicts of interest.
AL conceived the study, drafted the manuscript, collected data, and reviewed and revised the study. JA collected the data, drafted the manuscript, and reviewed the study. AU collected the data, drafted the manuscript, and reviewed the study. GMA conceived the study, drafted the manuscript, and reviewed the study.